^^^ Conversely, I'm also curious why Margaret is angry about Nucky's infidelities. IIRC, she was married to the other Irishman in the beginning of the series when she and Nuck got it on. Technically, she was the first to cheat and I got the impression she knew what she was getting into when she shacked up with him - she's not the naive country girl she pretends to be. Granted, it was a loveless and abusive relationship, but if she's adhering to the principals of Catholic marriage, she doesn't really have the moral high ground either, especially during that period in history when women were still technically the "property" of their husbands (not saying it's right - just saying that's how it was).
Eh...maybe I'm projecting, but at least with Nuck we always knew pretty much where he stood. He's a gangster and a dog with a bone. Not much pretense there, aside from the polish he puts on when working deals. While she does have an endearing interest at altruistically helping people (with the free clinic), Margaret also seems to ensconce herself in the blanket of faux piety and righteous moral indignation to obfuscate her own sins. Perhaps the clinic was her way of trying to change her spiritual course and right the wrongs of her past deeds. Now that the two things she seems to love in the world are gone (not including her kids), being that of the clinic and Owen (at the behest of Nucky), she may start doing some wacky things in the final 2 eps. Should be VERY cool.